The present invention generally relates to an apparatus and method of injection molding plastic articles. More specifically the present invention relates to an apparatus and method of injection molding multi-element plastic articles. Additionally, by using the apparatus and method of the present invention, each element of a multi-element plastic article may be formed from a separate molten plastic source. As such, a multi-element article may be formed with each element having a different plastic color, texture, or other plastic source characteristic. In the preferred embodiment, the apparatus and method contemplated by of the present invention are used to form multi-color molded fishing lures.
There are many types of artificial baits presently used by fishermen to attract and catch fish. One of the most popular of these baits is the molded plastic bait. Frequently these baits are molded to resemble, as closely as possible, the natural baits they are intended to replicate. Numerous lures are readily available that replicate worms, salamanders, crawfish, frogs, and the like. Molded plastic baits are also produced that do not physically resemble natural baits but attract fish by imparting an action in the water that a fish finds attractive. These baits and their natural bait replicas are often produced in different colors and textures that seem to attract fish for a particular set of weather and water conditions. It is believed that a molded plastic artificial bait with multiple elements and each element having its own plastic color, texture, or other plastic property would be desirable to attract and catch fish. With present manufacturing techniques the formed lures usually must be manually extracted from their mold cavities. Once removed excess plastic, known as flashing, needs to be removed from the formed lures to finish the article. Consequently, there is a need to make plastic lures by combining multi-element action with multi-element color combinations and to be able to manufacture these lures economically and efficiently.
It is an object of the present invention to provide an apparatus and method for injection molding multi-element plastic articles. A further object of the invention is to provide an apparatus and method for selectively injecting a separate source of molten plastic into each element of a multi-element plastic article, permitting variation of color, texture, or other plastic properties between elements of the formed article. Moreover, it is an object of the present invention to improve the speed and efficiency of the manufacturing process.
The first two objects of the present invention are achieved by interposing at least one selectively positionable separator bar between successive elements of multi-element cavities defined between movable and stationary mold plates. The multi-element cavities in the mold plates define an outer form of the multi-element article. Axially extensible mandrels, inserted within the multi-element cavities, successively define an inner article form for each element of the multi-element article. In an injection position, the separator bar isolates communication from a selected plastic source to a discrete element defined between an element of a multi-element mold cavity, a portion of the extensible mandrel and the interposed separator bar. Plastic from the selected plastic source is injected to the discrete element through a notch in the separator bar, forming a discrete article element. When separator bar is selectively positioned in a joining position, separator bar permits communication between the discrete element defined by its injection position and a successive element of the multi-element cavity and also permits axial extension of a mandrel section into the successive element cavity. Plastic from a selected source of molten plastic is then injected into the successive element cavity, forming the successive article element. Because in this position the separator bar allows communication with the adjacent elements, the selected source of molten plastic joins with the previously formed discrete element. By including multiple separator bars, successive elements may be formed and joined with a preceding element, each formed with a different plastic source. In the preferred embodiment, multi-element, multi-color fishing lures are produced.
Speed and efficiency of manufacture are achieved by configuring the mandrels to be pivotally inserted and retracted from between the stationary mold plate and an open movable mold plate. By this configuration, the finished molded articles may be lifted from the stationary mold plate cavities as the mandrels are pivoted from between the opened plates. The operator may then simply pluck the finished article from the end of the mandrel.